Internal combustion engines may be efficiently cooled by circulating a coolant through an engine block to extract heat to reduce a temperature of the engine block. The coolant is generally an aqueous solution of (mono) ethylene glycol (ethane-1,2-diol), e.g., antifreeze, thereby forming a mixture with a depressed freezing point relative to pure water. The use of water-based liquids with low freezing points as a heat-dissipating medium may prevent burst damage caused by the expansion of water as it freezes at temperatures below 0° C. After extracting heat from the engine block, the coolant may be flowed through a vehicle interior heating circuit to transfer heat to a heat exchanger that then uses the heat to warm a vehicle interior.
However, the inventors herein have recognized potential issues with the use of an antifreeze solution. As one example, although degradation of engine components due to expansion of water upon freezing may be effectively reduced if the concentration of the antifreeze solution in the coolant is sufficiently high, a higher percentage of ethylene glycol may decrease a heat capacity of the mixture since pure water has a higher heat capacity. Also, larger heat exchangers and greater rates of flow therethrough may be demanded due to a higher viscosity of ethylene glycol. By reducing the concentration of ethylene glycol in the coolant, smaller heat exchangers (for example, a vehicle radiator) and/or smaller rates of flow through the heat exchanger may be allowed thereby decreasing hydraulic losses so that a smaller pump capacity within the cooling system may be sufficient to dissipate the heat.
Furthermore, conventional antifreeze solutions used for internal combustion engines may comprise 50% water and 50% ethylene glycol with a freezing point of approximately −40° C. Such low temperatures are observed in sparsely populated parts of the world and/or for a short period over the space of a year, so that the use of such an antifreeze solution all year round does not improve cooling efficiency more than an antifreeze solution of a lower concentration of ethylene glycol. In addition, in climates where ambient temperatures are high, coolant containing ethylene glycol may not be desired.
Other attempts to address cooling systems with antifreeze solutions of higher ethylene glycol content than desired for efficient engine cooling include various methods for adjusting the concentration of ethylene glycol in the coolant. One example approach is shown by Lee in KR 101999017880. Therein, a fixed apparatus for automatically controlling a concentration of an antifreeze is described. The fixed apparatus is provided in order to improve productivity on an assembly line and to increase an efficiency of vehicle production by installing a control antifreeze tank to control and mix an antifreeze with water by a flow rate control valve and a water level control valve. The apparatus comprises an operating part for inputting a concentration value of the antifreeze based on the climatic conditions of an export area, a control unit for calculating a mixture of antifreeze and water relative to the input concentration value, a flow rate control valve and a water level control valve for discharging and controlling the mixture of antifreeze and water fed from an antifreeze tank and a water supply tank via the control unit, and a control antifreeze tank for storing the antifreeze mixture which is mixed from the antifreeze and the water.
In another example by Fujii et al in U.S. Pat. No. 4,513,696, a fixed, compact apparatus for charging a cooling liquid with a desired antifreeze concentration is included in an engine cooling system. The apparatus comprises an additional reservoir for storing an additive, such as an antifreeze solution, for example, a cooling water reservoir for storing cooling water, and a filler head, which is configured to connect to a coolant inlet of a cooling system of a motor vehicle engine with additional pipes extending between the additional reservoir and the filler head, and cooling water pipes between the cooling water reservoir. Additional control valves are provided in the additional pipes in order to control the quantity of the additive delivered to the engine cooling system according to the capacity of the cooling system and a desired concentration of the additive. Cooling water control valves are also provided in the cooling water pipes, in order to control the quantity of cooling water delivered to the engine cooling system according to the capacity of the cooling system and the desired concentration of the additive. The engine cooling system is thereby charged with cooling water containing the additive in the desired concentration.
Methods for addressing the issue of controlling coolant composition may also include internal devices on a vehicle to vary a concentration of antifreeze in an antifreeze solution or to alleviate other disadvantages of a cooling system having a high concentration of antifreeze. One example approach is shown by Park in KR 1999051956. Therein, an apparatus for automatically supplying an antifreeze solution of a vehicle and a control method to prevent a radiator and a cylinder block from being frozen and degraded is disclosed. The apparatus for automatically supplying an antifreeze solution of a vehicle comprises a vessel for storing antifreeze solution, on which an outlet opening is formed, which delivers the antifreeze solution to an underside of the vessel and which is fixed at a predefined position inside an engine hood of the vehicle. The apparatus further comprises a supply pipe, which is connected to a radiator, which contains coolant and is connected to the outlet opening, in order to deliver the antifreeze solution to the radiator. An opening and closing valve is fitted to the supply pipe in order to open and close a passage of the supply pipe. An outside temperature sensor registers the outdoor air temperature. A control unit opens and closes the opening and closing valve on the basis of a signal from the outside temperature sensor.
Another example is shown in KR 100250041 where a method is described for controlling the density of an antifreeze solution, in order to automatically control a density of the antifreeze solution as a function of the temperature of the outside air by increasing and reducing a quantity of cooling water via a centrifugal motor, and to deliver the antifreeze solution from a chamber. A density sensor measures the density of the antifreeze solution in a vehicle radiator. A control unit receives an input signal in the form of a signal from a temperature sensor, which registers the temperature of the outside air, and compares the density of the antifreeze solution and the temperature of the outside air with a predetermined logic. A control signal emitted by the control unit drives the centrifugal motor of a radiator reservoir tank to allow cooling water to flow out of the radiator. An antifreeze solution supply motor or a cooling water supply motor is driven to automatically deliver the antifreeze solution or the cooling water.
As another example, CN 104929752 discloses an adjusting device and a method of adjusting a liquid antifreeze of a cooling system of a turbocharged engine in order to decrease emission of loud flow noises, which in certain driving conditions are generated through the need to provide cooling liquid for the turbocharged engine. The adjusting device comprises a body control module (BCM), a relay and an open solenoid valve, the open solenoid valve being connected to a pipeline between a thermostat and a heat exchanger of the engine cooling system. The BCM is connected to one end of a coil of the relay. The other end of the coil of the relay is connected to a power supply B+. One end of a switch of the relay is connected to the power supply B+, the other end of the switch of the relay is connected to one end of the open solenoid valve. The other end of the open solenoid valve is grounded. The BCM collects an engine cooling water temperature signal, an engine speed signal and a vehicle speed signal and outputs signals after internal computation. An opening/closing of the open solenoid valve is controlled by the relay, in order to adjust the liquid antifreeze. The adjusting device and the method of adjustment serve effectively to prevent a noise from the liquid antifreeze flowing into the heat exchanger and to improve the ride comfort in a passenger compartment.
As another example, CN 201050401 describes an alternative solution to reducing degradation of engine components due to expansion of water upon freezing at outside temperatures below 0° C. This describes an antifreeze regulating device of a radiator which is matched to the radiator. The antifreeze regulating device is situated in a closed, hollow reservoir structure, one or more pores being arranged on the bottom. The entire device is arranged in a water lower water storage chamber of the radiator. The device is fixed on the underside of the lower water storage chamber by means of a fixing plate, two ends being closed. When the radiator is completely filled with cooling water and the water temperature increases, the volume of air enclosed in the antifreeze regulating device expands in order to reduce an ingress of cooling water from the lower water storage chamber. If the ambient temperature drops below 0° C., the air is cold and the volume of air contracts, the water is frozen and the volume is increased through the pores into the antifreeze regulating device, thereby reducing any expansion of the radiator due to the frozen water. The water storage structure of the radiator is therefore protected from a forced expansion.
As another example, U.S. Pat. No. 5,263,885 describes a device (electronic Winterizer”), which is installed in an interior of a boat. It winterizes an inboard/outboard engine without the involvement of a skilled person. The winterizing may be performed in or out of the water. The device allows a boat owner to operate his inboard/outboard engine in cold temperatures without each time having to ask a person to winterize the engine. The boat may thereby be used throughout the winter. To operate the device, the inboard/outboard engine is first started. Once the engine has reached a suitable temperature the thermostat is opened. While the engine is running, the operator operates a switch which is mounted on the dashboard of the control cabin. The switch activates an electronic timer that switches on a DC-powered valve and a pump. The instant it is switched on the valve opens and the pump starts. The pump pumps antifreeze from a storage tank, which is likewise installed inside the boat. The pump delivers antifreeze through the open valve into the injector. The injector is fitted in a hose, which provides coolant to the engine and the driveshaft. The antifreeze flows through the injector at an angle such that it mixes the antifreeze and the cooling water in a suitable ratio that prevents the unit from freezing.
However, the inventors herein have recognized potential issues with such systems. As one example, a size of the cooling system in the systems described above, including a tank for water and an additional tank for coolant, may occupy a large volume of space in a front compartment of a vehicle. In particular, heat exchangers may be bulky and impose space constraints on a positioning of other vehicle components. Pumping of the aqueous antifreeze mixture may also levy high hydraulic forces and drive torque at a water pump of the vehicle. Furthermore, once mixed, a concentration of antifreeze in the coolant mixture may not be reduced in response to an increase demand for cooling capacity. This may result in coolant mixtures with an undesirably high amount of antifreeze that results in increased loading on the water pump. If recirculation of the aqueous antifreeze mixture is not desired, the mixture may have to be stored onboard.
In one example, the issues described above may be addressed by a cooling system of a vehicle engine, comprising an engine cooling circuit, containing a coolant solution, and a vehicle interior heating circuit fluidly coupled to the engine cooling circuit, where a reservoir for receiving a concentrated antifreeze and a shutoff element, arranged in the flow between the reservoir and the vehicle interior heating circuit, are provided, and where the shutoff element serves to establish a flow connection between the reservoir and the vehicle interior heating circuit in at least one operating state of the cooling system. In this way, the size of the cooling system and hydraulic forces applied to pumping the coolant may be reduced.
As one example, the engine cooling circuit contains a liquid coolant and a vehicle interior heating circuit is fluidly coupled to the engine cooling circuit. A reservoir for receiving the concentrated antifreeze is provided and a shutoff element is arranged in a flow path between the reservoir and the vehicle interior heating circuit. The shutoff element may fluidly couple the reservoir to the vehicle interior heating circuit in at least one operating state of the cooling system. A separation unit may be provided for separating antifreeze out of the coolant solution of the engine cooling circuit. The separation unit may be fluidly coupled on an inlet side to the engine cooling circuit and on an outlet side to the reservoir and return the separated components of the coolant solution to individual tanks for each components. In this way, coolant solution and ethylene glycol may be recycled within the cooling system, reducing refilling events and storage of waste antifreeze solutions onboard. The cooling system may effectively decrease a likelihood of the coolant solution freezing and/or reduce a pump capacity for dissipating the heat. The use of a smaller heat exchanger and/or pipes of smaller diameter may be allowed as a result. As well, the concentrated antifreeze solution may be introduced into the engine cooling circuit via the vehicle interior heating circuit, so that existing systems may be retrofitted with the said cooling system.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.